Re: [Qemu-devel] [PATCH v2 02/19] spapr: introduce a skeleton for the XIVE interrupt controller

[David Gibson]

On Thu, Jan 18, 2018 at 08:27:52AM +1100, Benjamin Herrenschmidt wrote:
> On Wed, 2018-01-17 at 15:39 +0100, Cédric Le Goater wrote:
> > Migration is a problem. We will need both backend QEMU objects to be 
> > available anyhow if we want to migrate. So we are back to the current 
> > solution creating both QEMU objects but we can try to defer some of the 
> > KVM inits and create the KVM device on demand at CAS time.
> 
> Do we have a way to migrate a piece of info from the machine *first*
> that indicate what type of XICS/XIVE to instanciate ?

Nope.  qemu migration doesn't work like that.  Yes, it should, and
everyone knows it, but changing it is a really long term project.

> 
> > The next problem is the ICP object that currently needs the KVM device 
> > fd to connect the vcpus ... So, we will need to change that also. 
> > That is probably the biggest problem today. We need a way to disconnect 
> > the vpcu from the KVM device and see how we can defer the connection.
> > I need to make sure this is possible, I can check that without XIVE
> 
> Ben.
> 

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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